问题
填空题
已知⊙O1与⊙O2相切，圆心距是5，⊙O1的半径是3，则⊙O2的半径是 ______．
答案
设圆O2的半径是a，
当两圆相外切时，
∵圆心距是5，⊙O1的半径是3，
∴a+3=5，
∴a=2，
当两圆相内切时，a-3=5，
∴a=8，
故答案为：8或2．
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已知⊙O1与⊙O2相切，圆心距是5，⊙O1的半径是3，则⊙O2的半径是 ______．
设圆O2的半径是a，
当两圆相外切时，
∵圆心距是5，⊙O1的半径是3，
∴a+3=5，
∴a=2，
当两圆相内切时，a-3=5，
∴a=8，
故答案为：8或2．
| 用下列地点介词填空完成短文。 | |
3____________ our house there is a big school. 4____________ our house is Jim's house. Jim is a good friend of mine. At the moment we're sitting 5____________ my room. Jim is sitting 6____________ a chair and I am sitting 7____________ the floor. 8____________ me there are a lot of magazines. 9____________ the wall there are some pictures of me, my friends and my family. The sun wakes me up in the morning. I like living 10____________ this area. |